Irregular Water Flow displaying on DDS3

[subarusmasher]

I've recently been having a problem with my 2D + DDS3 system - When the engine is held WOT and 'on boost' and the system is active and flowing water, I am seeing a fluctuation in the number of illuminated bars on the DDS3 gauge. This seems to pulse from 5-2-5-2-5 bars illuminated as the engine revs out.

Prior to experiencing this issue, the gauge was set to illuminate 5 bars at peak flow, and seemed to work correctly.

I connected the purple (FI IDC) wire from the FIA2 unit to my datalogger, and the output can practially be overlaid onto the Petrol FIDC curve, and is a 'smooth' curve unlike the DDS3 visual display output - I assume this output curve from the FIA2 is correct, with WI 'mirroring' Petrol Injection Duty Cycle?

I have no leaks in the system, and cant see any air bubbles in any of the water lines.

All of the wiring install has been checked over and is fine.

The water tank is full of 50/50 water meth mix, is baffled, and it's internal priming pump can be heard running when the WI system is triggered.

The system is triggered at approx 20% FIDC

The system has an accumulator fitted. 22cc IIRC?

I am not experiencing any detonation even with the problem occuring, but want to get it resolved as my tune is running aggressive levels of ignition timing - circa 30 degrees at 20 psi.

I think i may have a problem with either the Race Pump or possibly the flow meter, although i would assume if the flow meter was faulty or blocked it would consistently under-read and show low flow levels on the gauge, rather than an pulsing water flow?

During a cold spell this winter, the water lines froze @ -10 outside temp - i was running 100% distilled water at the time - I thawed the system out and it didn't appear to have damaged the pump, as the system continued to work afterwards with no external leaks. - I wonder if this has in fact damaged the pump and has become the cause of my current issue.

Any help would be most appreciated, as i'm kind of stuck now